I'm trying to use the newlfm package to put together a LaTeX letterhead. (Thankfully, my college's letterhead is text-only, so I don't have to worry about fancy logos or the like.) I've gotten fairly close to making it work, but newlfm insists on putting horizontal rules below the letterhead (and above the footer, which is currently empty.)

How can I tell newlfm not to insert these rules? I know that newlfm uses fancyhdr under the hood, so I tried inserting the commands

\renewcommand{\headrulewidth}{0pt}
\renewcommand{\footrulewidth}{0pt}

in my preamble, but it didn't have any effect. (Explicitly loading fancyhdr didn't in the preamble didn't make a difference.) I also tried putting these commands inside the definition of the Williamsltr wrapper, but that didn't work either. The documentation doesn't seem to mention these horizontal rules at all.

Any thoughts? I'd like to use newlfm if at all possible, but if getting rid of these rules is more than a minor tweak, I'm open to using another package instead.